1. Field of the Invention
The present invention relates to wireless communication. More particularly, the present invention relates to a method for avoiding in-device interference in a terminal equipped with multiple heterogeneous communication modules.
2. Description of the Related Art
With the rapid popularization of smartphones, various radio technologies such as Wireless Local Area Network (WLAN), Bluetooth, and Global Positioning System (GPS) are widely used by means of the smartphones. In order to meet the various user requirements, it is now common for a portable terminal to integrate several communication technologies (e.g., cellular technology such as Long Term Evolution (LTE)/Universal Mobile Telecommunications System (UMTS), WLAN, Bluetooth, and Global Navigation Satellite System (GNSS)/GPS), which may potentially result in an inter-technology interference problem. This issue is under discussion in the name of In-Device Coexistence (IDC) in the 3rd Generation Partnership Project (3GPP).
The LTE/UMTS communication technology operates on various frequency bands while the Bluetooth and WLAN operate on the Industrial, Scientific and Medical (ISM) band of 2400˜2483.5 MHz. Among the frequency bands assigned for the LTE/UMTS communication, Band 4 (2300˜2400 MHz) and Band 7 uplink (2500˜2670 MHz) are close to the ISM band used by Bluetooth and WLAN such that the simultaneous operations of the two technology modules cause significant interference to each other.
In LTE, the Discontinuous Reception (DRX) operation is defined for reducing the power consumption of the User Equipment (UE). That is, the UE checks the downlink channel periodically so as to wake up only when downlink traffic is detected but remains in a sleep state when no downlink traffic is detected. In the LTE system of the related art, however, the DRX operation is designed in consideration only with the downlink traffic and thus the uplink traffic is transmitted regardless of the DRX pattern. Recently, the DRX technique is being considered to reduce interference. However, the DRX technique is limited in its ability to accomplish such purpose with the DRX of the related art, which cannot control the transmission signal (i.e., uplink signal) causing the actual interference.